No, I definitely read it properly.
By implying that light-to-medium intensity activity (such as sitting at the computer, which you provided as an example) is the best for burning fat (which is somewhat true - dietary fat is the primary macronutrient used as an energy source in resting state) you're misleading him into thinking that this is actually a GOOD way to burn fat, dietary or bodyfat.
If you want to burn fat, you do high-intensity work. Period. Heavy compound weight lifting, high-intensity interval training, sprinting, barbell complexes, metcon circuits, etc. That or long slow distance cardio - cycling or running.
Shoom, I suggest you make an effort to become more educated about the basics of nutrition and health as they will be essential to your ability to lead a healthy lifestyle, now and later in life.